An injection device which as a setting part has a graduated tube is known from U.S. Pat. No. 8,747,367. When setting an amount of injection fluid to be pressed or squeezed out, the graduated tube is moved in the distal direction. The graduated tube is moved in the opposite direction when the amount of injection fluid to be squeezed out or dispensed is being pressed out. The graduated tube is connected to the housing by way of a threaded connection such that the graduated tube, in addition to the movement in the distal or proximal direction, is also rotated in relation to the housing. Moreover, the injection device has a latching installation which acts between a threaded part and the housing. When setting the amount of injection fluid to be dispensed, the threaded part is rotated in relation to the housing. When the amount of injection fluid to be dispensed is being pressed out, the threaded part is guided in the axial direction in the housing such that the latching installation is not active when a dosage is being pressed out, there being no audible clicks of the latching installation.
The injection device known from U.S. Pat. No. 8,747,367 has fixed dosing increments. If and when, for example, amounts of 0.20 ml and 0.25 ml of injection fluid which are to be set for a therapy are required, then known injection devices are conceived such that dosing increments of at most 0.05 ml are settable. This means, on the one hand, that the user has to overcome a plurality of latching steps until he reaches the minimum dosage which is intended for the therapy. On the other hand, the amount of injection fluid which has to be discarded during the priming procedure is comparatively sizeable in the case of a minimum fixed dosing increment of 0.05 ml, for example. Therefore, significantly smaller dosing increments would be desirable for the priming procedure. However, this leads to a significantly increased number of latching positions which have to be overcome by the operator when setting the dosage.